Grinding machine



May 22, 1956 Filed Deo. 28, 1954 /r/Ql c. c. ALVORD GRINDING MACHINE 5Sheets-Sheet l Y L l| 5IN V EN TOR.

CHARLES C. ALVURJ:

Seite ATTNEY May 22, 1956 c. c. ALVORD GRNDING MACHINE 3 Sheets-SheetFiled Dec. 28, 1954 INVENToR. Y EHA/M55 CLALVUR'B AT TUR/VE Y May 22,1956 C, C, ALVORD 2,746,214

GRINDING MACHINE Filed Dec. 28, 1954 3 Sheets-Sheet 3 IN VEN TOR.

CHARLEE C. A/ VURII Mw.wm

ATTR'VEY United States Patent G 2,746,214 GRINDING MACHINE Charles C.Alvord, Worcester, Mass., assigner to Norton Company, Worcester, Mass.,a corporation of Massachusetts Application December 2S, 1954, Serial No.478,110 3 Claims. (Cl. 51-134.5)

The invention relates to grinding machines, and more particularly to aspeed control apparatus automatically to maintain a uniform peripheralspeed of the grinding wheel as it wears away.

One object of the invention is to provide a simple and thoroughlypractical speed control mechanism automatically to maintain asubstantially uniform peripheral speed on a grinding wheel. Anotherobject is to provide an automatically actuated rheostat control forvarying the speed of the grinding wheel driving motor so as to maintaina substantially constant peripheral speed of the wheel as it wears away.Another object is to provide an automatically actuated speed controlmechanism which is actuated by and in timed relation with the truingtool feeding mechanism for increasing the rotative speed of the grindingwheel as it wears away so as to maintain a substantially constantperipheral speed thereon. Another object of the invention is to providea cam actuated mechanism for controlling a standard rheostat orpotentiometer automatically to maintain a uniform peripheral speed ofthe grinding wheel as it wears away. Other objects will be in partobvious or in part pointed out hereinafter.

In the accompanying drawings in which is shown one of the variouspossible embodiments of the mechanical features of the invention:

Fig. 1 is a fragmentary side elevation of a grinding machine embodyingthe invention;

Fig. 2 is a hydraulic diagram of the actuating mechanism for the truingapparatus;

Fig. 3 is an electric wiring diagram of the control apparatus;

Fig. 4 is a fragmentary side elevation, on an enlarged scale, partlybroken away and shown in section, through the truing apparatus;

Fig. 5 is a fragmentary front elevation, on an enlarged scale, of thetruing apparatus;

Fig. 6 is a fragmentary rear elevation, on an enlarged scde, showing thecam and rheostat together with the actuating mechanism therefor;

Fig. 7 is a fragmentary sectional view on an enlarged scale, takenapproximately on the line 7-7 of Fig. 6 through the actuating cam andthe follower; and

Fig. 8 is a fragmentary sectional view, on an enlarged scale, takenapproximately on the line 8 8 of Fig. 6 through the rheostat actuatingmechanism.

A grinding machine has been illustrated in the drawings comprising abase 10 which serves as a support for a rotatable work support (notshown). This work support may be identical with that shown in the priorU. S. Patent No. 2,522,485 to H. A. Silven and C. G. Flygare, datedSeptember l2, 1950, to which reference may be had for details ofdisclosure not contained herein.

The base 10 serves as a support for a transversely movable wheel slide11 which is arranged to slide transversely on a V-way and at way (notshown) formed on the upper surface of the base 10.

A grinding wheel feeding mechanism is provided for imparting atransverse movement to the wheel slide 11 relative to the base 10comprising a half-nut 14 depending from the understide of the wheelslide 11. The half-nut 14 meshes with or engages a rotatable feed screw15. The feed screw 15 may be actuated by any of the well knownconventional feeding mechanisms, either manually or automatically.

The wheel slide 11 serves as a support for a rotatable grinding Wheelspindle 16 which is journalled in spaced bearing (not shown). The Wheelspindle 16 supports a grinding wheel 17 at one end thereof. The grindingwheel 17 is partially surrounded by a wheel guard 18 which is fastenedto the wheel slide 11.

A suitable driving mechanism is provided for the spindle 16 comprising avariable speed electric motor 2t) which is mounted on the upper surfaceof the Wheel slide 11. The motor 20 is provided with a motor shaft 21having a multiple V-grooved pulley 22 mounted thereon which is connectedby multiple V-belts 23 with a multiple V-grooved pulley 24 which ismounted on the right hand end of the wheel spindle 16. A rheostat orpotentiometer 25 having an actuating shaft 26 (Fig. 6) is provided forvarying the speed of the motor 20.

The wheel guard 1S supports a housing 30 having a plane upper surfacewhich in turn supports a bracket 31 for supporting a grinding wheeltruing apparatus. A slide base 32 is fixedly supported on the bracket 31by means of clamping screws 33 and 34. The slide base 32 serves as asupport for a longitudinally movable slide 35 which is arranged to slidelongitudinally on a dove-tailed slideway 36 (Fig. 4) formed on the slidebase 32.

A hydraulically operated mechanism is provided for traversing the truingapparatus slide longitudinally comprising a cylinder 37 which contains aslidably mounted piston 3S. The piston 33 is connected to the left handend of a piston rod 39 (Fig. 2), the other end of which is fastened toan end cap 4i) xedly mounted on the right hand end of the slide 35 (Fig.2). A pair of nuts 41 serve to lock the piston rod 39 to the end cap 40.The end cap 40 is provided with an adjustable stop screw 42 which isarranged to engage the right hand end of the cylinder 37 when the slide35 is traversed longitudinally toward the left (Fig. 2). When uid underpressure is passed through a pipe into a cylinder chamber 4.6, thepiston 38 together with the slide 35 will move toward the right (Fig.2). During this movement of the piston 38 uid within a cylinder chamber47 may exhaust through a pipe 48.

A control mechanism is provided for controlling the admission to andexhaust of fluid from the cylinder 37 comprising a rotary type valve 50having a valve rotor 51 which may be actuated manually by a. controllever 52. When fluid is passed through a pipe 53 from a suitable sourceof supply, it passes into a valve chamber 54, through a transversepassage 55 in the rotor 51 into a valve chamber 56 and through the pipe4S into the cylinder chamber 47 to cause the piston 33 to move towardthe left. This movement of the piston 38 and the slide 35 toward theleft continues until the stop screw 42 engages the right hand end of thecylinder 37. During this movement of the piston 38 toward the left, uidwithin the cylinder chamber 43 may exhaust through the pipe 45 into avalve chamber 57, through a transverse passage 58 in the valve rotor 51,into a valve chamber 59 and out through an exhaust pipe 60 and through athrottle valve 61. By manipulation of the throttle valve 61, the speedof movement of the piston 38 and the truing apparatus slide 35 may bereadily varied and controlled as desired.

When it is desired to reverse the direction of movement of the slide 35,the control lever 52 may be shifted in a clockwise direction into thebroken line position 52a (Fig. 2) which movement shifts the valve rotor51 so that luid under pressure from the pipe 53 passes into the valvechamber 57, through the pipe 45 into the cylinder chamber 46 to causethe piston 38 and the slide 35 to move longitudinally toward the right.During this movement fluid within the cylinder chamber 47 may exhaustthrough the pipe 48'into the valve chamber 56, through the transversepassage into the valve chamber 54 and out through the pipe 60 and thethrottle valve 61.

The longitudinally movable slide 35 serves as a support for a verticallyarranged housing 64. YThe housing 64 is provided with spaced `bearings65 and 66 (Fig. 4) which support a vertically arranged truing toolcarrier 67 Y havingfa truing tool 68 mounted at its lower end.

A feeding mechanism is provided for feeding the carrier 67 vertically ineither direction relative to the longitudinally movable slide 35. Thismechanism may comprisev a nut and screw feeding mechanism in whichV athreaded portion 69 is provided on the upper end of the carrier 67. Arotatable nut 70 meshes with or engages the threaded portion 69 andVisprovided with an integral ange71 which is rotatably supported on thecarriery 64 by a pair of plates 72 and 73. d

A manually operable feed wheel 75 is mounted on the lower end of avertically arranged rotatable shaft 76 which is rotatably supported in ahousing 77. The housing 77 is fixedly mounted relative to the housing64. The upper end of the shaft 76 is provided with a pinion 78 whichmeshes with a gear '79 keyed on the periphery of the nut 70. It will bereadily apparent from the foregoing disclosure that a rotary motion ofthe hand wheel 75 will be imparted through the mechanism above describedto rotate the nut 7 0 and thereby impart a Vertical axial movement tothe truing tool carrier 67. The direction of Vrotation of the hand wheel75 serves to determine the direction of movement of the carrier 67. Inorder to facilitate locking the carrier 67 in an adjusted position, aspring pressed detent 80 is provided which is arranged to engage theteeth of a gear 81 keyed on the upper end of the shaft 76. When it isdesired to adjust the position of the truing tool 68, the detent may bemoved in a direction toward the left (Fig. 4) to disengage the detentfrom the gear 81 after which the feed wheel 75 may be rotated to causethe desired vertical movement of the truing tool carrier 67 and thetruing tool 68.

As shown in Fig. 3, power lines 84 and 85 are provided for supplyingelectric power to the grinding wheel driving motor 20. A start switch 86is provided which when closed serves to energize a relay switch 87 whichwhen energized serves to pass current to the rheostat 25 to start themotor 20. A stop switch 88 is provided whereby the motor 20 may bestopped at any time during a grinding operation if desired.

In order to attain the main object of this invention, it is desirable toprovide an automatic control mechanism for the rheostat 25 so that asthe grinding wheel is reduced in diameter due to wheel wear and wheeltruing, an increase in speed is obtained by advancing the rheostat 25automatically. In the preferred construction the rheostat is preferablycontrolled by the down feeding movement of the truing apparatus so thatwhen the truing tool is fed toward the operative peripheral surface ofthe grinding wheel 17 for a truing operation, a corresponding motion isimparted t the rheostat control shaft 26 so as to adjust the rheostat asthe grinding wheel wears away. In the preferred construction aconventional type rheostat is provided and a cam controlled mechanism isinterposed between the truing tool feeding mechanism and the rheostatshaft so that as the wheel wears away a compensating adjustment isprovided for the rheostat to maintain a uniform peripheral speed. Asillustrated in the drawings a flexible shaft 9G is connected by acoupling 89 with the upper end of the shaft 7 6. The lower end of theexible shaft 90 is connected to a driveshaft 91 of a gear reduction unit92. The gear reduction unit illustrated is of a standard commercialVariety such as manufactured by the Boston Gear Works having a 150 to lreduction between .the drive shaft and the driven shaft. The gearreduction -unit 92 is provided with a driven shaft 93 (Fig. 7) whichsupports a cam plate 94 `havinga spiral cam groove 95 formed therein. Afollower roller 96 rides in the cam groove and-is supported by a stud 97on a slide bar 98. The left hand end of the slide bar 98 is providedwith an elongated slot 99 which is arranged to slide upon the rear endof the driven shaft 93 of the gear reducer unit 92. The other end ofVthe slide bar 98 is slidably supported within a bracket 100 which is inturn supported by a bearing 101 on the rheostat control shaft 26. Theslide bar 98 is provided with rack teeth 102 which meshY with a pinion103 which is keyed Yonto the rheostat shaft 26. The spiral cam groove 95is so shaped as to control the rate of actuation of the rheostat shaft26 in relation to the down feed of the truing tool so as to maintain aconstant Aperipheral speed of the grinding wheel as it wears away.v Itwill be readily apparent from the foregoing disclosure that when thetruing tool is fed vertically in a downward direction for a truingoperation, a compensating adjustment will be imparted .through themechanism above described to advance the rheostat so Y as to maintain aconstant peripheral speed on the grinding wheel.

It will thus be seen that there has been provided by this inventionapparatus in which the various objects hereinabove set forth togetherwith many thoroughly practical advantages are successfully achieved. Asmany possible embodiments may be made of the above invention and as manychanges might be made in the embodiment above set forth, it is to beunderstood that all matter hereinbefore set forth, or shown in theaccompanying ing wheel onV said spindle,` means including an electric vmotor on said slide to rotate said spindle, arrheostat on said slideoperatively connected t control the speed of said motor, a truingapparatus on said slide including a longitudinally movable slide movableparallel with the axis of the wheel spindle, a transversely movabletruing tool carrier on said slide, feeding mechanism interposed betweenthe truing apparatus slide and the carrier to feed the truing tooltoward and from the grinding wheel, means including a cam and arotatable follower operatively connected to actuate said rheostat, andoperative connections between the truing tool feeding mechanism and saidcam whereby actuation of the truing tool feeding mechanism automaticallyactuates the rheostat to Vadjust the Aspeed of said motor, said cambeing' shaped to control rate of actuation of the rheostat so as tomaintain a constant peripheral speed of the grindingwheel as it Wearsaway.

- 2. In a grinding machine llas claimed in claim 1,'in corn'- binationwith the parts and features therein specified iny which the cani andfollower mechanism comprises a slide bar to support said cani follower,and a rack and gear connection between the slide bar and rheostat toactuate said rheostat so as Vtd maintain a constant peripheral speed ofthe grinding wheel as itwea'rs away.y Y

3. In a grinding machine as claimed in claim l, in combination with theparts and features therein specified of a gear reducer unit on saidslide having a driving and a driven shaft, operative. connectionsbetween the truing tool feeding mechanism and the drive shaft, a cam onsaid driven shaft, a rotatable follower roller engaging said cam, aslide bar to support said follower roller, and a rack and gearconnection between the bar andrheostat to actuate said rheostat toadjust the speedof the motor so as to maintain a constant peripheralspeed of the grinding wheel as it wears away. Y

References Cited in the file of this patent r UNITED STATES PATENTS

